Fix crash on IP address change.

net/base/host_resolver.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_HOST_RESOLVER_H_
 #define NET_BASE_HOST_RESOLVER_H_
 
 #include <string>
 
 #include "base/ref_counted.h"
@@ skipping 149 matching lines @@
   virtual void CancelRequest(RequestHandle req) = 0;
 
   // Adds an observer to this resolver. The observer will be notified of the
   // start and completion of all requests (excluding cancellation). |observer|
   // must remain valid for the duration of this HostResolver's lifetime.
   virtual void AddObserver(Observer* observer) = 0;
 
   // Unregisters an observer previously added by AddObserver().
   virtual void RemoveObserver(Observer* observer) = 0;
 
-  // Gives the HostResolver an opportunity to flush state.
-  virtual void Flush() {}
-
   // Sets the default AddressFamily to use when requests have left it
   // unspecified. For example, this could be used to restrict resolution
   // results to AF_INET by passing in ADDRESS_FAMILY_IPV4, or to
   // AF_INET6 by passing in ADDRESS_FAMILY_IPV6.
   virtual void SetDefaultAddressFamily(AddressFamily address_family) {}
 
   // Returns |this| cast to a HostResolverImpl*, or NULL if the subclass
   // is not compatible with HostResolverImpl. Used primarily to expose
   // additional functionality on the about:net-internals page.
   virtual HostResolverImpl* GetAsHostResolverImpl() { return NULL; }
@@ skipping 57 matching lines @@
 // (Except if a unit-test has changed the global HostResolverProc using
 // ScopedHostResolverProc to intercept requests to the system).
 // |network_change_notifier| must outlive HostResolver.  It can optionally be
 // NULL, in which case HostResolver will not respond to network changes.
 HostResolver* CreateSystemHostResolver(
     NetworkChangeNotifier* network_change_notifier);
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_H_